#include<iostream>
#include<vector>

using namespace std;

bool cmp(vector<int> &A, vector<int> &B){
    if(A.size() != B.size()) return A.size() > B.size();
    for (int i = A.size() - 1; i >= 0; i -- )
      if(A[i] != B[i]) return A[i] > B[i];
    return true;
}

// c = A - B
vector<int> sub(vector<int> &A, vector<int> &B){
	vector<int> C;
	for(int i = 0, t = 0; i < A.size(); i ++ ){
	   t = A[i] - t;
	   if(i < B.size() ) t -= B[i];
	   C.push_back((t + 10) % 10);
	   if(t < 0) t = 1;
	   else t = 0;
	}
	while(C.size() > 1 && C.back() == 0) C.pop_back();
	return C;
  } 
  
int main(){
	string a, b;
	vector<int> A, B;
	
	cin >> a >> b;
	for(int i = a.size() - 1; i >= 0; i -- ) A.push_back(a[i] - '0');
	for(int i = b.size() - 1; i >= 0; i -- ) B.push_back(b[i] - '0');
	
	if(cmp(A, B)){
	    vector<int> C = sub(A, B);
	    for(int i = C.size() - 1; i >= 0; i -- ) cout << C[i];
	}
	else{
	    vector<int> C = sub(B, A);
	    printf("-");
	    for(int i = C.size() - 1; i >= 0; i -- ) cout << C[i];
	}
	return 0;
} 